This disclosure pertains to elevation of oleic acid content of commercial cottonseed oil using a non-GMO (genetically modified organism) strategy. This disclosure also relates to the identification of a high oleic seed variant and its use in monitoring the introgression of a naturally-occurring high oleic seed oil trait into cotton varieties, including Pima and upland cotton varieties.
Although cotton is farmed for its production of spinnable fibers, the residual seed after ginning is an important global source of vegetable oil. In fact, the yield of seed on a per acre basis is about 1.6 times that of the harvested fiber, and in 2012 this amounted to 5.37 million tons of cottonseed produced in the United States (USDA-Oil Crops Outlook). Currently less than half of the seed produced in the United States is crushed and processed into refined vegetable oil, and with world demand for vegetable oils on the rise, this represents a place for farmers to recognize additional value from their overall crop. Oilseeds and their refined vegetable oils vary in price based on their compositional formulations and end use markets. Due to its oxidative stability and flavor enhancing properties, cottonseed oil enjoys a reputation as an excellent frying oil, but with changes to its fatty acid composition, cottonseed oil might enter other markets (Lui et al., 2009; 2012). As with all natural products, the compositions of extracted products may vary from season to season, with environmental and genetic factors contributing to both desirable and undesirable components.
A more complete understanding of the many components in refined cottonseed oils and the factors which influence their formation within the embryo, may help to develop new varieties with consistent and highly desirable vegetable oil compositions. Detailed chemical analysis of seed oils (including minor components) within the context of different genotypes or environmental conditions could help to provide breeders with rich resources to enhance the overall value of the cotton crop. Moreover, the detailed analysis of lipid metabolites within embryos may offer insights into pathways and postharvest processes that influence seed viability and seedling vigor.
Vegetable oils are a major source of calories in most western diets, and their nutritional and physical properties are dependent upon their fatty acid composition. Important for improved oxidative stability is a reduced level of unsaturation, and until recently this was accomplished largely by the chemical hydrogenation of most vegetable oils. However, by-products of hydrogenation are trans-fatty acids and due to health concerns about these non-natural fats, other options for reduced polyunsaturated oils have been sought. Most desirable have been the development of crop varieties that produced seeds with high oleic oils, or enhanced monounsaturate-containing oils, as these oils have perceived health benefits and exceptional stability in frying applications. Most oilseed crops have now been developed with high oleic seed varieties through transgenic and/or non-transgenic means. With concerns expressed by some consumers about foods harboring so-called genetically modified organisms (GMO), and the lengthy, expensive prospects of de-regulating transgenic traits, there has been a keen interest to develop crops with altered seed oil compositions through breeding approaches rather than through targeted, transgenic techniques. The success of the breeding approach relies, in part, on an existing variant gene pool with diversity in the seed fatty acid composition. While there is considerable variation in fatty acid composition found in the genetic backgrounds of most major oilseed crops, upland cotton (Gossypium hirsutum, L.) has been reported to exhibit a rather narrow range in seed oleic acid content (˜15-20% of the total fatty acid composition) when large germplasm collections have been examined (Liu et al., 2009).